Salmon plasminogen and plasmin have been isolated and characterized. Salmon plasmin is 12 to 20 times more active than human plasmin. Salmon fibrinogen possesses a BBeta-chain larger than the AAlpha-chain. Laser light scattering is being employed to study the rigidity of lamprey crosslinked fibrin clots. SV40 transformed rabbit uterine Epithelial cells have been maintained in culture for a year. The AAlpha-subunits of lamprey fibrinogen, modified by succinic anhydride, are under study to elucidate the unusual structure.